JPH0686589A - Motor driving circuit - Google Patents

Abstract

PURPOSE:To provide a motor driving circuit for stably starting, at a high speed, a DC brushless motor having a snubber circuit for absorbing noise. CONSTITUTION:A snubber circuit 23b for absorbing spike noises generated in a driving coil of a spindle motor 22 is connected with the driving coil via a switch circuit 23c and CPU 29 controls this switch circuit 23c to disconnect the driving coil from the snubber circuit 23b at the time of starting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive circuit,
In particular, a DC having a snubber circuit for absorbing noise
The present invention relates to a motor drive circuit that drives a brushless motor.

[0002]

2. Description of the Related Art FIG. 9 shows a block diagram of a conventional hard disk device.

In the figure, reference numeral 1 denotes a magnetic disk as a recording medium. The magnetic disk 1 has a disk shape, and its center is fixed to the rotary shaft 2 a of the spindle motor 2. The spindle motor 2 is a brushless sensorless DC motor. A brushless sensorless DC motor has no mechanical parts such as a brush for supplying current to a rotor and a commutator corresponding to the brush, and a position detection element such as a hall sensor for detecting a rotor position. There is no DC motor. The spindle motor 2 is connected to the spindle motor drive circuit 3 and rotates at a constant speed in response to a drive signal from the spindle motor drive circuit 3 to rotate the magnetic disk 1 at a constant speed.

A magnetic head 4 is provided close to the magnetic disk 1, and the magnetic head 4 causes the magnetic disk 1 to move.
Information is recorded on the above or information on the magnetic disk 1 is reproduced. The magnetic head 4 is connected via an arm 5 to a voice coil motor 6 that moves the magnetic head 4 in the radial direction (direction of arrow A). The voice coil motor 6 is connected to the voice coil motor drive control circuit 7, and in response to a drive signal from the voice coil motor drive control circuit 7, the rotary shaft 6a.
To rotate the magnetic head 4 in the radial direction (arrow A direction).

The voice coil motor drive control circuit 7 is connected to the tracking control circuit 8 and generates a drive signal for driving the voice coil motor 6 according to the tracking control signal supplied from the tracking control circuit 8. The tracking control circuit 8 is connected to the CPU 9 and the signal processing circuit 10, moves the magnetic head 4 to the command track of the CPU 9 in response to a track command signal from the CPU 9, and controls the magnetic field in response to an error signal from the signal processing circuit 10. A control signal for causing the head 4 to scan the recording track Tr ₀ is generated.

The signal processing circuit 10 is connected to the magnetic head 4 and the control circuit 11 in addition to the tracking control circuit 8, processes the signal read by the magnetic head 4 to generate a tracking error signal, and the tracking control circuit 8
Is supplied to the control circuit 11 to generate reproduction data.
Supply to. The signal processing circuit 10 also performs signal processing such as modulation on the recording data from the control circuit 11 and supplies the recording data to the magnetic head 4.

In addition to the signal processing circuit 10, the control circuit 11 includes C
It is connected to the PU 9 and the interface control circuit 12, is controlled by the CPU 9, supplies reproduction data to the interface control circuit 12, and inputs recording data from the interface control circuit 12. The interface control circuit 12 is connected to a host computer (not shown), supplies various commands from the host computer to the CPU 9, and transmits data between the host computer and the magnetic disk 1 via the control circuit and the signal processing circuit 10. Exchange.

FIG. 10 shows a circuit configuration diagram of a main part of a conventional example. The stator portion of the spindle motor 2 is composed of drive coils L ₁ , L ₂ and L ₃ connected in a Y shape. The drive coils L ₁ , L ₂ and L ₃ are the spindle motor drive control circuit 3a.
Is connected to one end of the drive coil L ₁ and the drive signal φA,
The drive signal φB and the drive coil L are connected to one end of the drive coil L _2.
The drive signal φC is supplied to one end of ₃ . The other ends of the drive coils L ₁ , L ₂ and L ₃ are connected to a common terminal.

FIG. 11 shows a waveform diagram of the drive signals φA, φB and φC. The drive signals φA, φB, and φC are in phase with each other by 12
It is considered that the trapezoidal waves differ by 0 °. From time t _{0 to} t ₁ , the drive signal φB goes high and the drive signal φA goes low. Therefore, the current i flows through the drive coil L ₂ → L ₁ as shown in FIG. Since the drive signal φB is at the high level and the drive signal φC is at the low level from time t _{1 to} t ₂ , the current i flows through the drive coil L ₂ → L ₃ as shown in FIG. 12B. Since the drive signal φA is at a high level and the drive signal φC is at a low level from time t _{2 to} t ₃ , the current i is equal to the drive coil L ₁ as shown in FIG.
→ Flows to L ₃ . Since the drive signal φA is at the high level and the drive signal φB is at the low level from time t _{3 to} t ₄ , the current i flows through the drive coil L ₁ → L ₂ as shown in FIG. Since the drive signal φB is at the low level and the drive signal φC is at the high level from time t _{4 to} t ₅ , the current i flows through the drive coil L ₃ → L ₂ as shown in FIG. Since the drive signal φA is low level and the drive signal φC is high level from time t _{5 to} t ₆ , the current i is shown in FIG.
As shown in (f), the current flows to the drive coil L ₃ → L ₁ .
As shown in FIGS. 12A to 12E, the current i sequentially flows through the drive coils L ₁ , L ₂ , and L ₃ , so that a rotating magnetic field is generated in the stator and the rotor magnetized with multiple poles is rotated. It

However, as shown in FIG. 11, the drive signal φ
At the rise and fall of A, φB, and φC, noise 13 is generated by the back electromotive force of the drive coils L ₁ , L ₂ , and L _3.
Will occur. Therefore, as shown in FIG. 10, the driving coil L _1, L _2, L ₃ resistance between R ₁ to R _3, consists capacitors C ₁ -C _3, a snubber circuit 3b for removing noise 13 is not connected It was

The snubber circuit 3b is a CR circuit in which a resistor R ₁ and a capacitor C ₁ are connected in series, a CR circuit in which a resistor R ₂ and a capacitor C ₂ are connected in series, and a CR circuit in which a resistor R ₃ and a capacitor C ₃ are connected in series. and connect the circuit to the Y-shaped, the ends of the CR circuit of each configuration were respectively connected to the driving coil L _1, L _2, L _3, a driving coil L _1, L _2, spike noise 13 generated in L ₃ It was configured to be absorbed by the CR circuit. Here, the amount of generated noise (starting stability) with respect to the circuit constant of the snubber circuit 3b has a characteristic as shown in FIG. For this reason, if the circuit constant is determined so as to reduce the amount of generated noise, the starting stability is reduced.

[0012]

However, since the snubber circuit is fixedly connected to the drive coil in the conventional motor drive circuit, the start-up becomes unstable due to the power loss due to the snubber circuit at the time of starting the motor, and the start-up is fast. There was a problem that it could not be done.

The present invention has been made in view of the above points, and an object of the present invention is to provide a motor drive circuit capable of high-speed and stable starting.

[0014]

According to the present invention, a motor having noise removing means for removing noise generated in a plurality of drive coils, which is connected to a plurality of drive coils for generating a rotating magnetic field by being supplied with drive signals of different phases. In the drive circuit, a switch means connected between the plurality of drive coils and the noise removing means for connecting and disconnecting the drive coils and the noise removing means, and a switch means for turning off the switch means when the motor is started. Switch control means for disconnecting the plurality of drive coils and the noise removal means, and turning on the switch means during steady operation of the motor to connect the plurality of drive coils to the noise removal means. It becomes.

[0015]

According to the present invention, it is possible to disconnect the plurality of drive coils and the noise removing means at the time of starting the motor, and to connect the plurality of drive coils and the noise removing means at the time of steady operation of the motor. Therefore, since the power loss due to the noise removing means can be eliminated at the time of starting the motor, high-speed and stable starting can be performed, and noise generated in the drive coil can be removed by the noise removing means during the steady operation of the motor. A stable steady operation is possible.

[0016]

1 is a block diagram of an embodiment of the present invention.

In the figure, reference numeral 21 indicates a magnetic disk as a recording medium. The magnetic disk 21 has a disk shape, and its center is fixed to a rotary shaft 22 a of a spindle motor 22.
The spindle motor 22 is composed of a brushless sensorless DC motor, is connected to a spindle motor drive circuit 23, and rotates at a constant speed in response to a drive signal from the spindle motor drive circuit 23 to drive the magnetic disk 21 to rotate at a constant speed.

The magnetic disk 21 has a magnetic head 2
4 are provided close to each other, and information is recorded on the magnetic disk 21 by the magnetic head 24 and information on the magnetic disk 21 is reproduced. The magnetic head 24 is connected via an arm 25 to a voice coil motor 26 that moves the magnetic head 24 in the radial direction (direction of arrow A). The voice coil motor 26 is connected to the voice coil motor drive control circuit 27, and rotates about the rotary shaft 26a in response to a drive signal from the voice coil motor drive control circuit 27 to move the magnetic head 24 in the radial direction (arrow A). Direction).

The voice coil motor drive control circuit 27 is connected to the tracking control circuit 28 and generates a drive signal for driving the voice coil motor 26 according to the tracking control signal supplied from the tracking control circuit 28. The tracking control circuit 28 is connected to the CPU 29 and the signal processing circuit 30, and drives the magnetic head 24 to the CPU 29 in response to a track command signal from the CPU 29.
Signal processing circuit 3 while moving to the command track from
A tracking control signal for causing the magnetic head 24 to scan the recording track Tr ₀ is generated according to the error signal from 0.

The signal processing circuit 30 is connected to the magnetic head 24 and the control circuit 31 in addition to the tracking control circuit 28, processes the signal read by the magnetic head 24 to generate a tracking error signal, and the tracking control circuit. 28, and also generates reproduction data and supplies it to the control circuit 31. Further, the signal processing circuit 30 subjects the recording data from the control circuit 31 to signal processing such as modulation and supplies the recording data to the magnetic head 24.

The control circuit 31 includes C in addition to the signal processing circuit 30.
It is connected to the PU 29 and the interface control circuit 32, is controlled by the CPU 29, supplies reproduction data to the interface control circuit 32, and inputs recording data from the interface control circuit 12. The interface control circuit 32 is connected to a host computer (not shown), supplies various commands from the host computer to the CPU 29, and controls the circuit 31 and the signal processing circuit 3.
Data is exchanged between the host computer and the magnetic disk 21 via 0.

FIG. 2 shows a block diagram of the essential parts of an example of the present invention. The stator portion of the spindle motor 22 is composed of drive coils L ₁₁ , L ₁₂ , and L ₁₃ connected in a Y shape. The drive coils L ₁₁ , L ₁₂ , and L ₁₃ are connected to the spindle motor drive control circuit 23 a, and one end of the drive coil L ₁₁ has a drive signal φA, and one end of the drive coil L ₁₂ has a drive signal φB and a drive coil L ₁₃ . The drive signal φC is supplied to one end. Also,
The other ends of the drive coils L ₁₁ , L ₁₂ , and L ₁₃ are connected to a common terminal.

The driving coil L _11, L _12, L drive coil L ₁₁ is between _13, L _12, L ₁₃ consisting of the capacitor C ₁₁ -C ₁₃ in order to remove the spike noise generated in the snubber circuit 2
3b is connected through the switch circuit 23c.

The snubber circuit 23b includes a capacitor C ₁₁ ,
The C _12, C ₁₃ and connected to the Y-shaped, each switching circuit 23c
Is connected to the drive coils L ₁₁ , L ₁₂ , and L ₁₃ via the switching elements Q ₁ , Q ₂ , and Q ₃ , respectively, and spike noise generated in the drive coils L ₁₁ , L ₁₂ , and L ₁₃ is converted into a capacitor. A CR circuit formed by the resistances of C ₁₁ , C ₁₂ , C ₁₃ and switching elements Q ₁ , Q ₂ , Q ₃ absorbs it. Incidentally, the snubber circuit 23b in this embodiment is constituted only by the capacitor _{C 11, C 12, C 13} , spike noise constitute a CR circuit with the resistance possessed by the switching elements Q _1, Q _2, Q ₃ of the switch circuit 23c , But snubber circuit 23b
Alternatively, a resistor may be separately provided.

The switch circuit 23c is a switching element Q.
₁ , Q ₂ , Q ₃ , resistor R ₁₁ , capacitor C ₁₄ , and inverter INV ₁ . Switching elements Q ₁ , Q ₂ , Q
₃ is a P-channel MOS type FET, the source is the drive coil L ₁ , L ₂ , L ₃ , and the drain is the snubber circuit 23 b.
Is connected to the capacitors C ₁₁ , C ₁₂ , and C ₁₃ , and the gate is connected to the output of the inverter INV ₁ . The output of the inverter INV ₁ is applied with a constant voltage V _C via a resistor R ₁₁ and grounded via a capacitor C ₁₄ . The input of the inverter INV ₁ is connected to the CPU 29. FIG. 3 shows a circuit configuration diagram of the inverter INV ₁ . As shown in FIG. 3, the inverter INV ₁ is composed of an NPN transistor Q ₄ and resistors R ₁₂ and R ₁₃ and is called a so-called digital transistor.

The base and the emitter of the transistor Q ₄ are connected to each other via the resistor R ₁₃ , the base is connected to the input terminal T _IN via the resistor R ₁₂ , and the collector is the output terminal T.
It is configured to be connected to _OUT . Inverter INV
₁ is the transistor Q when the input terminal T _IN goes high
_{When 4} turns on and the output terminal T _OUT goes low, and when the input terminal T _IN goes low, the transistor Q ₄ turns off and the output terminal T _OUT goes high.

The switch circuit 23c is an inverter INV ₁ when the snubber control signal from the CPU 29 is high level.
Output becomes low level and switching elements Q ₁ , Q
_Since the gates of ₂ and Q ₃ become low level, the switching elements Q ₁ , Q ₂ and Q ₃ are turned off, and the snubber circuit 23b
Is cut from the drive coils L ₁₁ , L ₁₂ , and L ₁₃ .

Whether the switch circuit 23c is the CPU 29 or not
When the snubber control signal is low level, the inverter I
NV₁Output becomes high level and switching element Q
₁, Q₂, Q₃Since the gate of becomes high level,
Touching element Q₁, Q₂, Q ₃Turns on the snubber circuit
23b is a drive coil L₁₁, L₁₂, L₁₃Connect with. this
At this time, the resistance R of the switch circuit 23c₁₁Is set to an appropriate value
The switching element Q₁, Q₂, Q₃Is on
It does not turn on completely, has some resistance, and snubbs
Capacitor C of path 23b₁₁, C₁₂, C₁₃With CR circuit
Is configured to absorb spike noise.
There is. Therefore, the snubber circuit 23b does not need a resistor.
It

Next, the operation of the apparatus will be described. FIG. 4 is a flowchart for explaining the operation at startup, FIG.
FIG. 6 shows an operation waveform diagram.

First, when the device is in the stopped state, the magnetic
The head 22 is a CSS (contour) that is not affected by motor noise.
Start / Stop) area (not shown)
is doing. When the power of this device is turned on, the time t₁₁At C
The motor-on signal of PU29 (Fig. 5 (A)) is high level.
To low level. Motor on signal goes low
Then, the spindle motor drive control circuit 23a, the drive signal
Nos. ΦA, φB, and φC are drive coils for the spindle motor 22.
Le L₁₁, L₁₂, L₁₃Is supplied to the spindle motor 22
Is activated (step S1). 5, time t₁₁At a point
When the motor-on signal is output, the output signal
Low level) spindle motor drive control circuit 2
The switching frequency (PLL) shown in FIG.
Signal) supply switch is turned on. Time t₁₁Well then
Non-startable high switching frequency that is set from the beginning
Starts with a number of preset, startable low
Gradually decrease until a high switching frequency is reached (t₁₁→ t
₁₂). Time t₁₂From the same movement as a stepping motor
Start to boot. Back electromotive force from unused phase
After being able to study (time t₁₃), Time t
₁₃By gradually increasing the oscillation frequency from the time
The motor rotation speed (time t₁₃~ T ₁₄). Su
After a few seconds, the pindle motor drive control circuit 23a
Whether the PLL control of the motor is locked, that is, the rotation of the motor
Judge whether it has become constant or not, and still be in the locked state
Wait until it locks (time t₁₃~ T₁₄) With lock
Then, time t₁₄The sync signal supplied to the CPU 29 with
-Level (steps S2, S3, S4). next,
The CPU 29, which has received the sync signal, receives time t₁₅Switch on
Send a snubber on signal (high level) to the path 23c
Switch on the switch circuit 23c and connect with the snubber circuit 23b
Yes (step S5).

A snubber on signal at time t ₁₅ (FIG. 5 (E))
Switch circuit 2
The signal supplied to the gates of the switching elements Q ₁ , Q ₂ and Q ₃ by the capacitor C ₁₄ provided in 3c is shown in FIG.
As shown in (A), the high level is gradually decreased to the low level, and the switching elements Q ₁ , Q ₂ , and Q ₃ are gradually turned on. Thus, FIG. 6 (B) ~ driving coil L ₁₁ as shown in (D), L _12, drive signals φA supplied to L _13, [phi] B, stable rotation can be performed without the rapid change in [phi] C. When the snubber circuit 23b is connected and a current flows, spike noise (motor noise) 33 is removed, and the magnetic head 24 is moved for the first time (step S6). And the host CPU on the computer side
When management data for connecting this device (not shown) to this device is read, and the interface control circuit 32 accepts the management data, it is connected to the host CPU to exchange information data (steps S7 and S8).

According to the present embodiment as described above, at the time of motor start driving the snubber circuit 23c coil L _11, L _12, L
_Since it can be cut off from _{13, the} loss due to the snubber circuit 23c can be eliminated, and high-speed and stable activation can be performed.

The switch circuit 23c shown in FIG.
A configuration including a relay switch 34 and a diode D ₁ as shown in FIG. However, in such a configuration, since the relay switch 34 cannot have a resistance, the snubber circuit 23b needs to be configured by a CR circuit including a capacitor C ₀ and a resistor R ₁₅ .

Further, when the snubber circuit 23b is composed of a CR circuit, as shown in FIG.
_A configuration is also conceivable in which ₁₅ is biased by resistors R ₁₂ and R _{13 so} that it acts as only a switch.

Further, as shown in FIG.
Le MOSFET Q₁₆Resistance R₁₄, R ₁₅Bias with
The snubber circuit 23b is configured to have a resistance even when it is turned on.
Capacitor C₀Drive coil L₁₁, L₁₂, L₁₃On the side
A configuration of connecting may be considered. Also, as shown in FIG.
In this embodiment, the snubber on signal from the CPU 30 is used.
And the inverter INV₂Through the resistor R₁₆，
R₁₇P-channel MOSFET Q biased by₁₆
It is also possible to use a configuration for driving the.

Further, as shown in FIG. 8B, it may be considered that the photo-MOS relay switch 35 includes a light-emitting diode D ₂ , photo-MOS transistors Q ₈ and Q ₉ , and diodes D ₃ and D ₄ . In such a circuit, the on-time can be controlled by the resistor R ₁₈ which determines the current of the light emitting diode D ₂ .

[0037]

As described above, according to the present invention, since the noise removing circuit can be cut at the time of starting regardless of the influence of noise, the loss due to the noise removing circuit can be eliminated at the time of starting, and the starting stability can be improved. It has features such as being able to improve

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a main part of an embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of another main part of an embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 5 is an operation waveform diagram of one embodiment of the present invention.

FIG. 6 is an operation waveform diagram of one embodiment of the present invention.

FIG. 7 is a configuration diagram of a modified example of a main part of an embodiment of the present invention.

FIG. 8 is a configuration diagram of a modified example of a main part of one embodiment of the present invention.

FIG. 9 is a block diagram of a conventional example.

FIG. 10 is a circuit configuration diagram of a main part of a conventional example.

FIG. 11 is an operation waveform diagram of a conventional example.

FIG. 12 is a diagram illustrating an operation of a conventional example.

FIG. 13 is a characteristic diagram of generated noise amount (starting stability) with respect to the circuit constant of the snubber circuit.

[Explanation of symbols]

21 magnetic disk 24 magnetic head 22 spindle motor 23 spindle motor drive circuit 23a spindle motor drive control circuit 23b snubber circuit 23c switch circuit 29 CPU L ₁₁ , L ₁₂ , L ₁₃ drive coil

Claims (1)

[Claims] 1. The drive signals are sequentially supplied in different phases,
In a motor drive circuit that is connected to a plurality of drive coils that generate a rotating magnetic field and has a noise removal unit that removes noise generated in the plurality of drive coils, the motor drive circuit is connected between the plurality of drive coils and the noise removal unit. Switch means for connecting and disconnecting the drive coil and the noise removing means, and turning off the switch means when the motor is started to disconnect the plurality of drive coils from the noise removing means,
When the motor is in steady operation, turn on the switch means,
A motor drive circuit comprising: a switch control unit that connects the plurality of drive coils to the noise removal unit.